Radiotelegraphy



J. H. HAMMOND, JR. RADIOTELEGBAPHY. APPLICATION nun um 2a. 1913. nsuswso um. 8. I920.

Patented Aug. 24, 1920.

UNITED STATES PATENT OFFICE.

JOHN HAYS HAMMOND, JR., 0F GLOUCESTER, MASSACHUSETTS.

RADIOTELEGRAPHY.

Specification of Letters Patent.

Patented Aug. 24, 1920.

Application filed May 28, 1913, Serial No. 770,315. Renewed January 8, 1920. Serial No. 350,248.

To all whom it may concern,-

Be it known that I, J OI-IN I'IAYB I'IAMMOND, Jr., a citizen of the United States, residing at Gloucester, in the State of Massachusetts, have invented certain new and useful Improvements in Radi'otelegraphy, of which the followin is a specification.

My invention relates to systems for transmitting signals and messa es and for controlling mechanisms at a distance by means of radiant energy, and relates more particularly to transmitting apparatus .which onables signals to be sent so that they effect only the receiving station they are intended for, and no other.

In the accompanying drawings Figure 1 shows a transmitting station, in diagrammatic form, with a movable inductance coil in one position.

Fig. 2 shows the same transmitting station with the said inductance coil in another position.

In the figures, A is an antenna in circuit with an inductance coil L and grounded at E. A hi h-frequency alternating-current generator l is in circuit with an inductance coil L, and the condenser C is in a shunt circuit. The coil L is rotatable on the ivots D and F, so as to vary the mutual inductance between it and the coil L. In Fig. 1, coil L is shown in its osition of minimum mutual inductance with coil L, and in Fig. 2 in its position of maximum mutual inductance with coil L. A key K closes and opens a circuit includin the battery Ti and the electromagnet M. in Fig. 1 key K is open, and in Fig. 2 it is closed.

The movable core or plun or N of the electromagnet M is connecte' at one end by a rod to the piston P which travels in the cylinder 0 and is normall held near the left end of the cylinder by t e compressionspring S. The small. pipe Q connects both ends of the cylinder 0, and allows the an. or other fluid in the cylinder topass only slowly from one end to the other, so that the piston and the plunger N can travel only slowly in both directions. Attached to the other end of the plunger N is the rod H which is connected to a crank or bent arm l'" on the ivot F in such a way that as the plunger is rawn into the electromagnet M, the coil L is rotated into its po sition ofmaximum mutual inductance with thefcoil L, and when the electromagnet is deenergized and the plunger N moves away from the electromagnet under the influence of the spring S, the coil L is rotated into its position of minimum mutual inductance with the coil L.

When in o eration, the generator Gr is sending highre uenc'y alternatin currents through the coil L, but if the key is open, so that the electromagnet M is deenerglzed and the coil L is in its position of minimum effectiveness, as shown in Fig. 1, coil L will have little, if any, effect in inducing oscillations in the coil L and antenna circuit AL I), and there will be little, if any, radia tion of electric waves from the antenna A. When, however the key K is closed, so that electromagnet M is energized, plunger N drawn in, and coil L turned into its position of maximum effectiveness, as shown in Fig. 2, it will induce powerful oscillations in coil L and antenna circuit A. L E, and electric waves will be strongly radiated from antenna A.

' own to the dashot arrangement of piston and'c'ylinder in connection with plunger N, the latter can move only slowly and the movement of the coilL' will take place gradually, so that there will be no sharp makes and breaks in the trains of electric waves radiated from antenna A.

At a corresponding receiving station, which is not shown in the drawings, the receiving circuits are tuned to the wave length of the transmitting station, but the receiving apparatus 'will be actuated only when the coil L at the transmitting station is at or near its position of maximum mutua'l inductance with the coil L. When the key K is closed, this position is reached so radually, inthe manner already descri ed, that the transmitted energ will likewise increase gradually and smoothly, so that there will be no sharp breaks or sparks which will affect a para'tus at other receiving stations not 0 osely in tune with my transmitting station.

,Although only'o'ne of the forms in which thls invention may be embodied has been disclosed herein, it is to be understood that the invention is not limited to the specific "form shown but might be ap lied in various forms without departing rom the spirit "of the invention or the scope of the appended claims.

Having thus described my invention, I claim 1. In a radio transmission system, a

transmitting station comprising a generator of high-frequency electrical oscillations, a movable inductance coil in circuit therewith, an electromagnet, means for energizin r said electromagnet, means controlled by sai electromagnet for moving. said inductance coil, means for retarding the movement of said coil, and an antenna circuit having a coil in inductive relation to said movable inductance coil.

2. In a radio transmission system, a transmitting station comprising a generator of high-frequency electrical oscillations, a movable inductance coil in circuit therewith, a solenoid, means for energizing said solenoid, a core arranged to be reciprocated by said solenoid and operatively connected to said coil to move the same, means for retarding the movement of said solenoid, and an antenna circuit having a coil in inductive relation to said first mentioned coil.

3. In a radio transmission system, a transmitting station comprising a generator of higlrirequcney electrical oscillations, a movable inductance coil in circuit therewith, a solenoid, means for energizing said solenoid, a core arranged to be reciprocated by said solenoid and operatively connected to said coil to move the same, means for retarding the movement of said solenoid, yielding means normally holding said solenoid in a predetermined position, and an antenna circuit having a coil in inductive relation to said first mentioned coil.

4. In a radio transmission system, a transmitting station comprising a generator of high-frequency electrical oscillations, an inductance coil in circuit therewith and arranged to oscillate about a fixed axis extending substantially diametrically of said coil, said coil normally resting in a predetermined initial position in a given plane, actuating means automatically operative to swing said coil about said axis through a predetermined are into an operative posi tion, yielding means automatically operative to return said coil into said initial position, means automatically operative to retard the movement of said coil in either direction, and an antenna circuit including a coil normally arranged in a plane interseeting said first mentioned plane.

5. In a radio transmission system, the combination with means for emitting radiant energy, including two elements, one of which is movable with respect to the other to progressively vary the radiant energy emitted by said means, of actuating means automatically operative to cause a relative movement between said elements, and means tfor retarding the action of said actuating means.

\ operative 6. In a radio transmission system, the combination with means for emitting radiant energy, including two elements one of which is movable with respect to the other to progressivel vary the radiant energy emitted by sai means, of actuating means automatically operative to cause a relative movement between said elements, means for retarding the action of said actuating means, and means automatically operative to return one of said elements into an initial position after it has been moved therefrom by said actuating means.

7. In a radio transmission system, the combination with means for emitting radiant energy, including two elements one of which is movable with respect to the other to progressively vary the radiant energy emittedby said means, of actuating means automatically operative to cause a relative movement between said elements, means for retarding the action of said actuating means, and yielding means automatically operative to return one of said elements into an initial position after it has been moved therefrom by said actuating means.

8. In a radio transmission system, a transmitting station comprising a generator of high-frequency electrical oscillations, an inductance coil in circuit therewith and arranged to oscillate about a fixed axis and normally resting in a redetermined plane, means for automatical y swinging said coil about said axis through an arc of approximately ninety degrees, means automatically to return said coil to an initial position, and an antenna circuit having a stationary inductance coil arranged in a plane approximately perpendicular to the ilane of said first mentioned coil when in its said initial position.

9. In a radio transmission system, a transmitting station comprising a generator of high-frequency electrical oscillations, an inductance coil in circuit therewith and arranged to oscillate about a fixed axis extending transversely of said coil, said coil normally resting in a predetermined initial position in a given plane, means automatically operative to swing said coil about said axis through a predetermined are into an operative position, yielding means automatically operative to return said coil to said initial position, and an antenna circuit including a coil normally arranged in a plane intersecting said first mentioned plane.

This specification signed and witnessed this 26 day of May, A. D., 1913.

JOHN HAYS HAMMOND, JR.

Signed in the presence of M. J. Coornn, Sam A. THORNTON. 

